1. Field of the Invention
The present invention generally relates to data processing and more particularly to aging queries.
2. Description of the Related Art
Databases are computerized information storage and retrieval systems. The most prevalent type of database is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways.
Regardless of the particular architecture, a requesting entity (e.g., an application or the operating system) demands access to a specified database by issuing a database access request, or query. Such queries may include, for instance, simple catalog lookup requests or transactions and combinations of transactions that operate to read, change and add specified records in the database. The term “query” denominates a set of commands for retrieving data from a stored database. Queries take the form of a command language that lets programmers and programs select, insert, update, find out the location of data, and so forth. One well-known high-level query language is the Structured Query Language (SQL). Illustratively, SQL is used to make interactive queries for getting information from and updating a database such as International Business Machines' (IBM) DB2, Microsoft's SQL Server, and database products from Oracle, Sybase, and Computer Associates.
Queries are constructed of query conditions that serve to filter results returned from the query. Accordingly, a query may be thought of as group of filters put together to sift out irrelevant data and return only the data of interest. Often, it may be desirable to modify one or more of the query conditions and re-execute the query to determine the effects of the query condition on the results returned. For example, for a given query, the user may desire to see only that data added to a database since the last time the query was run. In the context of life sciences, consider a researcher tracking the effects of a disease over the course of a two year study. The researcher may periodically wish to check that there are not new candidates that can be brought into the study. The periodic collection of new data is required in other environments as well, such as in financial reporting, batch task distribution and order placement.
Conventionally, to limit query results to data added since the last execution of a query, requires reconstructing the query. For example, an additional temporal condition or conditions may need to be added to the query, whereby the query is restricted to specific time domain. However, this approach requires that the user track when queries were last run and have sufficient proficiency with queries in order to properly configured the queries with the proper temporal conditions.
Therefore, there is a need for an approach facilitating time-restricted queries configured to return results limited to those results that satisfy a given query and were added to the database since the last execution of the query.